Evaluation of the Potential of Plant Aggregates from Corn and Sunflower Stalks for the Design of Building Materials

Abstract

This work has been realized within the framework of Action No. 4 of the SAVASCO collaborative project (EFA353/19/SAVASCO) co-funded by INTERREG POCTEFA (INTERREG V-A Spain - France - Andorra 2014–2020). This action was carried out between June 2020 and May 2022, and is devoted to the development and characterization of a constructive solution based on corn and sunflower stalks as raw material. At the end of Action No. 3 of the project, different fractions of plant aggregates from corn and sunflower stalks were produced. The objective of Action 4 is to formulate different construction materials and products from these raw materials. The present paper will focus on the mechanical and thermal behavior of samples made of lightweight earth and concrete implemented by vibrocompaction at laboratory scale, as a model for prefabricated construction products assembled in a dry state on site. The influence of the nature of the aggregate on the properties of the composites was studied by working on the entire crushed stalks of corn, but also on sunflower pith and bark fractions produced from the separation process developed in the project. Finally, the influence of the particle size distribution of the sunflower bark particles was also evaluated. In the entire experimental campaign, hemp shives were used as the reference aggregate. Considering the binders, a commercial formulated lime binder was selected as well as two alternative clay binders produced locally in the regions of Tarbes, France and Barcelona, Spain. The first part of the paper summarises the main physical characteristics of the different aggregate fractions studied: bulk and particle densities, particle size distribution, water absorption, mechanical behavior and thermal conductivity. Some of these characteristics are used as formulation parameters for composites, others could be indicators to correlate with the performance of composites. The second part aims to evaluate the thermal and mechanical performance of composites formulated from these fractions. The highly anisotropic character of these composites and the significant influence of the nature of the particles and binders is highlighted. Several fractions, in particular from sunflower stalks, show a definite potential as an alternative plant aggregate to hemp shiv, in regions where the availability of the latter is limited. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.